Haemophilus Influenzae B is one of the bacteria that causes severe meningitis, sepsis, and pneumonia. Meningitis is characterized by fever, headaches, vomiting, and disturbances in consciousness state. The bacteria causes severe morbidity and poses the patients at risk for permanent neurological damage including retardation, seizures, deafness, and even mortality. The majority of the morbidity is among children at the ages of 4-5 years.

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The vaccine contains a small particle from the Haemophilus bacteria, and therefore it cannot cause a significant disease. It is a very safe vaccine and does not cause severe adverse effects. During the first 24 hours after the vaccination, there could be some local adverse effects which include redness, tenderness, and swelling of the area in which the vaccine was administered, or a slight fever. These effects can last for 2-3 days following the vaccination.   

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In Nepal, the vaccine is administered in three doses, according to the National childhood immunization program at the ages of 6, 10 and 14 weeks. According to the latest data from the WHO it is estimated that 87% of the population is vaccinated.